Channels estimation in OFDM system on block-type and comb-type pilot arrangement

Abstract

In orthogonal frequency division multiplexing (OFDM) systems over time-varying and frequency-selective fading channel, channel estimation and tracking is generally carried out by transmitting known pilot symbols in given positions of the frequency-time grid. The conventional approach of estimation can be split into two steps. First, estimating the received symbol over the pilot subcarrier and then early estimate signal is interpolated or smoothed over the entire frequency-time grid. Several methods have been introduced especially on block-type and comb-type pilot arrangement. Precise channel estimation will be proposed to improve synchronization in time-varying and frequency-selective fading channel without increasing the complexity and also sacrifice the bandwidth efficiency of the OFDM system.